negative voltage spike

Discussion in 'The Projects Forum' started by khaled ragab, Jan 25, 2013.

  1. khaled ragab

    Thread Starter New Member

    Aug 5, 2011
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    hello,
    i have a problem, if we have a coil e.g. lamp or any electrical devices in home(or conactors) that is controlled by a switch if i switch off the coil it is supposed to make a voltage spike(positive or negative) my question is how does home devices survive this voltage spike i know the answer if the spike is positive they use regulators but what if the spike is negative, does they use a special type of ac to dc converter that is not affected by the ac variation even if it is negative
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Many electronic devices powered by the electrical mains have "surge arrestors" built-in.
    The electricity mains can produce a very high current that has only a small effect from a voltage spike.
    A voltage spike is attenuated when it passes through a transformer because a power transformer cannot pass high frequencies.
     
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  3. khaled ragab

    Thread Starter New Member

    Aug 5, 2011
    12
    0
    thanks for the help but i have another question, i found that in the wiring system they use ground bar as the neutral does this cause a problem when switching of coils
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    488
    It improves the readability of your post if you use whole sentences? Like:

    "Thanks for the help but i have another question. I found that in the wiring system they use ground bar as the neutral. Does this cause a problem when switching of coils?"



    Is your question purely theoretical or are you talking about a specific application/device?

    There are millions of different electronic devices and each of them will have a different sensitivity to voltage disturbances. There is no general answer to your question.
     
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  5. khaled ragab

    Thread Starter New Member

    Aug 5, 2011
    12
    0
    thanks, the original problem is that i use an lcd in an electronic circuit and some contactors both circuits are split and as i switch off the coil of the contactor the voltage stepped down and the lcd get blanked(i think the circuit is switch off and powerd up again) so to get a dc voltage for my electronic circuit i use a transformer and bridge rectifier and capacitor, but the transformer is connected to the line and the neutral which is ground(both are connected together) does this cause any problem i know that i should split the ground and the neutral for safety but does it make any problem in voltage variations
     
  6. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Provide a schematic and a picture of your layout.
     
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  7. khaled ragab

    Thread Starter New Member

    Aug 5, 2011
    12
    0
    it is not available for me now all i want to know is it normal to connect the neutral to the ground while using a transformer
     
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